Fused filament tuft and fused brush strip

ABSTRACT

A fused filament tuft includes a plurality of filaments which are fused on at least one end to form a cluster or tuft. A cross section of the tuft of filaments may have any shape, such as round, rectangular, or oval. The fused filament tufts fabricated from metallic filaments may be formed by fusing at least one end with a welding process and then cutting the plurality of filaments. Filaments fabricated from synthetic materials may be fused into tufts with sonic welding and then cut to length. A nonfused end of each tuft may be flared by squeezing the perimeter of the tuft at substantially the fused end thereof. A plurality of tufts may be captured to form a brush with a base structure. A fused brush strip is an unified lengthwise progression of metallic filaments which may exceed twenty inches. The fused brush strip does not require a base structure to retain a plurality of filaments. The filaments are joined on one end thereof. The fused brush strip is preferably formed with a welding process. A nonfused end of the fused brush strip may be flared with squeezing dies. The fused brush strip may be flexed into a nonlinear shape and held by a retaining mechanism.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates generally to brush clusters andmore specifically to a fused filament tuft which retains a plurality offilaments in a cluster that allows for greater fill density than otherprior art manufacturing processes. The present invention also relatesgeneral to brushes and more specifically to a fused brush strip withgreater flexibility than that of the prior art.

[0003] 2. Discussion of the Prior Art

[0004] There are numerous ways of retaining a plurality of filaments toform a brush element. With a knot type brush, wires are twisted into aknot shape. Knotted wires have to be trimmed to yield consistent wireends. With pencil type brushes, wires are either clamped, swaged, orglued and retained in a wire holder. Combinations of the above may alsobe inserted into the wire holder. Wires are usually retained in the wireholder by friction. Using friction alone cannot guarantee the wires fromcoming out of the wire holder. Swaging tends to distort the wire holderwhose dimension is crucial for fitting into a tool.

[0005] With a staple set, a bundle of wires are bent into an U-shapedtuft and then stapled onto the brush assembly. Wires are held inside thebrush assembly by the friction of stapling wire relative to the brushassembly. Using friction alone cannot prevent the wires from pulling outof the brush assembly. The staple set technique is impractical forretaining a large quantity of filaments.

[0006] Laced tuft is similar to the staple set technique. A bundle ofwires are bent into a U-shaped tuft and then tied by a lacing wire atthe bottom of the U-bend. The laced tuft technique cannot be used inhigh-speed power brush applications. The laced tuft technique isimpractical for retaining a large quantity of filaments. The U-shapedwire tuft has to be trimmed if a consistent filament is required.Crimped wire brushes are manufactured by passing wires through crimpingdevices to impose a sinusoidal waveform on the straight wires. Then abundle of crimped wire is bent around a securing device such as a pin,wire or ring. The wire ends have to be trimmed to yield a consistentbrush face.

[0007] Traditional strip brush manufacturing typically bends filamentsabout a retaining wire to form a U-shape which is retained in a channelformed in a base. The filament density is largely limited by theretaining components. The flexibility of a strip brush is alsodetermined by the channel. Precision brush strips have been recentlyutilized in the sealing of turbine shafts and the shrouding of turbineblade housings.

[0008] It is well known in the art to weld a retaining rail to at leastone side of a plurality of filaments to form a strip brush. Theretaining rails add an extra thickness to the strip brush which reducesits effectiveness. The flexibility of the brush strip is limited by theretaining rails.

[0009] Accordingly, there is a clearly felt need in the art for a fusedfilament tuft which has a greater fill density than prior artmanufacturing processes, allows the combining of greater numbers offilaments than prior art manufacturing processes, and does not requiresecondary trimming of the filaments. There is also a clearly felt needin the art for a fused brush strip with no retaining rails which allowsthereof to have less width and greater flexibility than that of theprior art.

SUMMARY OF THE INVENTION

[0010] The present invention provides a fused filament tuft which issuperior to other prior art manufacturing processes in several ways. Afused filament tuft includes a plurality of filaments which are fused onat least one end to form a cluster or tuft. A cross section of the tuftof filaments may assume any shape, such as round, rectangular, or oval.When using metallic filaments, the tufts may be formed by positioning abundle of metallic filaments in a vertical orientation and preferablyfusing one end thereof with TIG welding. Other fusing processes besidesTIG welding may also be used. The bundle of metallic filaments ispreferably retained in a collet, guide tube, or the like and advanced toprovide the proper length for cutoff. Cutting an end off the bundleprovides a tuft. Cutting is executed with any suitable process. Theother end of a fused filament tuft may also be welded to produce adouble fused filament tuft. Filaments fabricated from syntheticmaterials may be fused into tufts with sonic welding, but other fusingprocesses may also be used.

[0011] A nonfused end of each tuft may be flared by squeezing theperimeter of the tuft at substantially the fused end thereof. It ispreferably to have two sets of squeezing dies which open perpendicularto each other. A plurality of tufts may be captured to form a brush. Thefused ends of each tuft may be captured by various mechanical means suchas molding, swaging, interference fit, or brazing to form a brush with abase structure.

[0012] The present invention also provides a fused brush strip which ismore flexible than that of the prior art. The fused brush strip is anunified lengthwise progression of metallic filaments which can exceedtwenty inches. The fused brush strip does not require a base structureto retain a plurality of filaments. The filaments are joined on one endthereof. The fused brush strip is created by first retaining thefilaments in a holding fixture. The holding fixture is traversedlengthwise with a constant speed relative to an electron beam of anelectron beam welding machine or an electrode of a TIG welding machine.One end of each of the filaments are welded such that they form a singlelengthwise assembly.

[0013] Accordingly, it is an object of the present invention to providea fused filament tuft which requires no secondary trimming.

[0014] It is a further object of the present invention to provide afused filament tuft which may be easily retained in a base structure toform a brush.

[0015] It is yet a further object of the present invention to provide afused filament tuft which has a large area of filament distribution at anonfused end.

[0016] It is yet a further object of the present invention to provide afused filament tuft which allows all filaments to be maintained inprecise parallelism to each other.

[0017] It is yet a further object of the present invention to provide adouble fused filament tuft which may be easily handled and trimmed at alater time.

[0018] It is yet a further object of the present invention to provide afused brush strip which does not require a base structure to retain aplurality of filaments.

[0019] Finally, it is another object of the present invention to providea fused brush strip with flared filaments which has a wider distributionof filaments at a nonfused end.

[0020] These and additional objects, advantages, features and benefitsof the present invention will become apparent from the followingspecification.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021]FIG. 1 is a perspective view of a fused filament tuft with a roundcross section in accordance with the present invention.

[0022]FIG. 1a is a perspective view of a fused filament tuft with arectangular cross section in accordance with the present invention.

[0023]FIG. 1b is a perspective view of a double fused filament tuft witha round cross section in accordance with the present invention.

[0024]FIG. 2 is a perspective view of a plurality of filaments retainedin a collet before fusion in accordance with the present invention.

[0025]FIG. 3 is a perspective view of two sets of squeezing dies whichare used to indent the filaments in a fused tuft to cause a nonfused endto be flared in accordance with the present invention.

[0026]FIG. 4 is an enlarged perspective view of a squeezing die inaccordance with the present invention.

[0027]FIG. 4a is an enlarged cross sectional view of a single squeezedie in accordance with the present invention.

[0028]FIG. 5 is a side view of a fused filament tuft after thereof hasbeen squeezed in accordance with the present invention.

[0029]FIG. 6 is a perspective view of a base structure which has beenswaged to retain a plurality of fused filament tufts to form a brush inaccordance with the present invention.

[0030]FIG. 7 is a perspective view of a base structure which has beenmolded or sintered around a plurality of fused filament tufts to form abrush in accordance with the present invention.

[0031]FIG. 8 is a partially exploded perspective view of a basestructure which has interference fit holes for receiving a plurality offused filament tufts to form a brush in accordance with the presentinvention.

[0032]FIG. 9 is a perspective view of a fused brush strip with filamentsoriented perpendicular with respect to the length thereof in accordancewith the present invention.

[0033]FIG. 10 is a perspective view of a plurality of filaments beingretained in a fixture before fusion of one end thereof to form a brushstrip in accordance with the present invention.

[0034]FIG. 11 is a perspective view of a fused brush strip withfilaments oriented at a prescribed angle with respect to the lengththereof in accordance with the present invention.

[0035]FIG. 12 is a perspective view of a set of squeezing dies which areused to indent filaments in a fused brush strip to cause a nonfused endto be flared in accordance with the present invention.

[0036]FIG. 13 is a perspective view of a fused brush strip after thereofhas been squeezed in accordance with the present invention.

[0037]FIG. 14 is a perspective view of a fused brush strip formed in acurved shape to be received by a brush seal assembly in accordance withthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0038] With reference now to the drawings, and particularly to FIG. 1,there is shown a perspective view of a fused filament tuft 1. The fusedfilament tuft 1 includes a plurality of filaments 10 which are fused onat least one end to form a cluster or tuft. With reference to FIG. 1a, across section of the fused filament tuft may have any shape, such asround, rectangular, or oval. A rectangular shape is shown in FIG. 1a.With reference to FIG. 1b, a double fused filament tuft 2 includes theplurality of filaments 10 which are fused on both ends. One of the fusedends 14 may be cut off to provide an open end.

[0039]FIG. 2 shows a bundle of metallic filaments 12 retained by acollet 100 in a vertical orientation. The metallic filaments 12 arepreferably fused on one end to form a tuft using an electrode 102 of aTIG welding operation, but other methods of fusing the metallicfilaments may also be used. After the bundle of metallic filaments 12are fused on one end, the bundle of metallic filaments 12 are cut tolength to form the fused filament tuft 1. The cutting operation may beimplemented with a shear cutter, water jet, or any other suitableprocess. Filaments fabricated from synthetic materials may be fused intotufts with sonic welding, or any other suitable fusing process.

[0040] With reference to FIGS. 3-5, a nonfused end of each fusedfilament tuft 1, may be flared by squeezing the perimeter of thefilaments 10 at substantially a fused end 14 thereof. It is preferablyto have a first set of squeezing dies 106 and 107 which openperpendicular to a second set of squeezing dies 108 and 109. Eachsqueezing die has a contoured cavity 110 to receive the cross section ofthe fused filament tuft 1. The contoured cavity 110 preferably has apointed edge 112 cross section to form an indentation 16 in theperimeter of the fused filament tuft 1.

[0041] A plurality of fused filament tufts 1 may be captured in a basestructure to form a brush. With reference to FIG. 6, a plurality offused filament tufts 1 are retained in a base structure 18. A lengthwiseretention cavity 20 with two walls is formed in an end of the basestructure 18. The lengthwise retention cavity 20 is sized to receive thefused end 14 of each fused filament tuft 1. After the plurality of fusedfilaments tufts 1 are inserted into the lengthwise retention cavity 20,the side walls 22 of the lengthwise retention cavity 20 are swaged overthe plurality of fused ends 14.

[0042] With reference to FIG. 7, a plurality of fused ends 14 arecaptured in a base structure 24 which is plastic molded around the fusedends 14. The base structure 24 could also be formed by sintering. Withreference to FIG. 8, a plurality of tuft holes 28 are formed in a basestructure 26. Each tuft hole 28 may be sized to have an interference fitwith the fused end 14 of each fused filament tuft 1. Each tuft hole 28may also be sized to slidably receive the fused end 14 of each fusedfilament tuft 1. The fused ends 14 would also be brazed to the basestructure 26.

[0043] With reference to FIGS. 9 and 10, a brush strip 30 is an unifiedlengthwise progression of metallic filaments 10 which may exceed twentyinches. The fused brush strip 30 does not require a base structure toretain the plurality of filaments 10. The filaments 10 are joinedtogether on a fused end 32. Preferably, the brush strip 30 is created byfirst retaining a bundle of metallic filaments 13 in a holding fixture34. The holding fixture 34 is traversed lengthwise with a constant speedrelative to an electron beam of an electron beam welding machine or anelectrode 104 of a TIG welding system. One end of each of the metallicfilaments 13 are fused such that they form a single lengthwise assembly.

[0044] With reference to FIG. 11, an angled fused brush strip 36includes a plurality of filaments 10 which are oriented at a prescribedangle with respect to the length thereof and are joined together on afused end 38.

[0045] With reference to FIG. 12, a pair of squeezing dies 112 arepositioned on both sides of the fused brush strip 30 at substantiallythe fused end 32. The pair of squeezing dies 112 are brought together toform a flared nonfused end as shown in FIG. 13. The squeezing dies 112form an indentation 40 in both sides of the fused brush strip 30.

[0046] With reference to FIG. 14, the fused brush strip 30 is flexed toform a curved portion of a turbine seal. The fused brush strip 30 iscaptured between a first retainer 114 and a second retainer 116. Thefirst and second retainers are secured with a plurality of fasteners118. The fused brush strip 30 may be flexed into other nonlinear shapes.

[0047] While particular embodiments of the invention have been shown anddescribed, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention inits broader aspects, and therefore, the aim in the appended claims is tocover all such changes and modifications as fall within the true spiritand scope of the invention.

I claim:
 1. A method of making a brush strip comprising the steps of:(a) retaining a lengthwise bundle of filaments; (b) fusing one end ofsaid lengthwise bundle of filaments; and (c) cutting said lengthwisebundle of filaments to form said brush strip.
 2. The method of making abrush strip of claim 1 wherein: said lengthwise bundle of filamentsbeing retained in a vertical orientation when being fused.
 3. The methodof making a brush strip of claim 1 wherein: said lengthwise bundle offilaments being retained in an angled orientation when being fused. 4.The method of making a brush strip of claim 1 wherein: fusing said endof said lengthwise bundle of filaments with a welding process.
 5. Themethod of making a brush strip of claim 4 wherein: said welding processbeing performed by moving said lengthwise bundle of filaments in alengthwise direction relative to one of an electron beam of an electronbeam welding machine and an electrode of a TIG welding machine.
 6. Themethod of making a fused brush strip of claim 1, further comprising thestep of: (d) flaring a nonfused end of said fused brush strip bysqueezing both sides of said fused brush strip at substantially a fusedend thereof with at least one set of squeezing dies.
 7. The method ofmaking a fused brush strip of claim 1, wherein: said fused brush stripbeing flexed into a nonlinear shape.
 8. The method of making a fusedbrush strip of claim 1, wherein: said fused brush strip being heldbetween a first and second retainer.
 9. A method of making a brush stripcomprising the steps of: (a) retaining a lengthwise bundle of filamentsin a vertical orientation; (b) fusing one end of said lengthwise bundleof filaments; and (c) cutting said lengthwise bundle of filaments toform said brush strip.
 10. The method of making a brush strip of claim 9wherein: fusing said end of said lengthwise bundle of filaments with awelding process.
 11. The method of making a brush strip of claim 10wherein: said welding process being performed by moving said lengthwisebundle of filaments in a lengthwise direction relative to one of anelectron beam of an electron beam welding machine and an electrode of aTIG welding machine.
 12. The method of making a fused brush strip ofclaim 9, further comprising the step of: (d) flaring a nonfused end ofsaid fused brush strip by squeezing both sides of said fused brush stripat substantially a fused end thereof with at least one set of squeezingdies.
 13. The method of making a fused brush strip of claim 9, wherein:said fused brush strip being flexed into a nonlinear shape.
 14. Themethod of making a brush strip of claim 13 wherein: said fused brushstrip being held between a first and second retainer.
 15. A method ofmaking a brush strip comprising the steps of: (a) retaining a lengthwisebundle of filaments in an angled orientation; (b) fusing one end of saidlengthwise bundle of filaments; and (c) cutting said lengthwise bundleof filaments to form said brush strip.
 16. The method of making a brushstrip of claim 15 wherein: fusing said end of said lengthwise bundle offilaments with a welding process.
 17. The method of making a brush stripof claim 16 wherein: said welding process being performed by moving saidlengthwise bundle of filaments in a lengthwise direction relative to oneof an electron beam of an electron beam welding machine and an electrodeof a TIG welding machine.
 18. The method of making a fused brush stripof claim 15, further comprising the step of: (d) flaring a nonfused endof said fused brush strip by squeezing both sides of said fused brushstrip at substantially a fused end thereof with at least one set ofsqueezing dies.
 19. The method of making a fused brush strip of claim14, wherein: said fused brush strip being flexed into a nonlinear shape.20. The method of making a brush strip of claim 19 wherein: said fusedbrush strip being held between a first and second retainer.